1. Field of the Invention
This invention relates to a hoist ring assembly.
2. Description of the Prior Art
Hoist rings are widely used for the attachment and usually the lifting of loads and heavy objects by cranes etc. Often it is desired to have pivotal and rotatable maneuverability of the hoist ring to allow the position of the hoist ring or load to be manipulated during the lifting, transportation or lowering of the load.
Several hoist rings claim to provide pivotal and rotatable movement, e.g. GB Patent No. 2306154A and U.S. Pat. No. 5352056. However these rings involve the screwing of a stud into the load as the only form of attachment between the ring and the load. Upon lifting, any rotating load could rotate about the thread of the stud rather than with the stud, i.e. slip and become loose from the ring. Such a situation is obviously not safe and not desirable. Moreover, changing the stud for different loads or different situations is not a quick and simple task.
It is an object of the present invention to provide a hoist ring which can be securely attached to a load, be continuously rotatable, and which is rapidly changeable.
According to one aspect of the present invention, there is provided a hoist ring assembly securable to a load plate comprising an elongate central stud having a threaded shank portion at least at the top end means to carry a load plate at the bottom end, a rotatable ring located above the load plate and secured about the stud by an upper nut on the upper threaded portion of the stud, and a bail pivotally secured to the ring, the load plate being securable against the ring,
Preferably, an intermediate integral transverse collar is provided and the means for carrying the load plate is the other end of the stud having a threaded position engagable by a lower nut.
The integral collar of the present invention provides a fixed and extended meeting surface against which a load plate can be fully tightened, and which will not therefore slip and separate during lifting and turning of the load plate. The lower end of the stud also has a threaded portion. The shank of the stud directly below the collar could have a non-circular cross-section, e.g. square or another profiled shape, which fits into a correspondingly shaped slot or aperture in the load to prevent any rotation, and thus separation, between the stud and load plate on turning.
The load plate could be fastenable to the stud either by having a threaded slot into which the lower threaded portion of the stud can be fitted and secured by a nut, or by an aperture in the load plate beneath which a nut could be located onto the lower threaded portion. One major type of prior art device used for lifting apertured loads is a threaded eyebolt with, a nut securing the load to the shank of the eyebolt. However, rotation of the load acts directly on the nut, lending to significant wear and thus expected failure. This is avoided by the present invention as the load plate, the collar and therefore the stud are together held fast.
The collar could have a shaped circumference to help tighten it and the stud to the load plate, e.g. square or hexagonal for a spanner. The collar could be smaller, of similar width, or wider than the ring above it.
The ring is preferably shorter in height than the distance between the collar and the upper nut when fastened, to allow the ring to rotate as freely as possible. Either the shank of the stud between the collar and the upper threaded portion could be wider than the threaded portion, providing a shoulder onto which the upper nut could be tightened, or an elongate bushing could be added around the stud shank above the collar, which bushing is longer than the height of the ring.
A shouldered shank or a bushing allows the upper nut to be tightened onto the assembly with maximum torque. The upper nut could also or otherwise be secured in place to prevent any rotation relative to the stud with other means such as with a split pin through aligned slots in the top nut and shank of the stud. The top nut could also be a self-locking nut.
The ring may be of any suitable shape, size or design. Generally, the ring is cylindrical with a smooth bore for free rotation about the stud.
The hoist ring assembly preferably includes a washer between the top nut and the ring, and a washer between the load and any bottom nut. More preferably, the assembly includes, either as the top washer or in addition thereto, a reduced friction washer, e.g. a plain or roller bearing or thrust race, between the top nut or any top washer and the ring. A reduced friction washer could conveniently fit in the gap between the ring and the upper nut or washer if a shouldered shank or bushing as described above is used.
The bail may be pivotally secured to the ring in a number of ways. Preferably two co-axial shoulder pins pass through aligned apertures in the ends of a xe2x80x9cUxe2x80x9d shaped bail and the main ring. To help secure the shoulder pins in place, roll pins could extend through aligned apertures in the ring and shoulder pins transverse to the axis of the shoulder pins.
The hoist ring assembly of the present invention could be used to lift any suitable form or shape of load, whether industrial, agricultural, or domestic. One suitable load is the swivel plate of the lifting device as described in co-pending UK Patent Application No. 9619845. In combination, many forms and shapes, including odd shapes, can easily be lifted, transported and rotated by any suitable means, e.g. a material handler.
The stud could have means at one or both ends other than a threaded shank to allow it to be fastened to or secured to an overlying fastening means other than a nut, e.g. an apertured collar and fastening pin. Such other means can also fasten and/or secure the stud to the other parts of the assembly and/or the load. The invention is not therefore limited to the use of threads and nuts, although such would generally be used.
According to a second aspect of the present invention, there is provided a hoist ring assembly securable to a load plate comprising an elongate central stud having a threaded shank portion at each end and an intermediate integral transverse collar, a swivel shackle located above the collar and secured about the stud by an upper nut on the upper threaded portion of the stud, the load being securable against the lower face of the collar and fastenable to the stud using the lower threaded portion.